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  • 1.
    Al-Ashor, Safana
    University of Borås, Faculty of Textiles, Engineering and Business.
    Sustainable food packaging based on polyhydroxyalkanoate2024Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The Norwegian Food Research Institute (Nofima) and the University of Borås worked together to develop this project. The commonly used packaging materials pose a serious threat to the environment, as they are produced from nonrenewable crude oil and cannot decompose naturally. Despite some manufacturers' claims of their products being eco-friendly or sustainable, they are not entirely made from renewable resources and are not biodegradable. Nevertheless, some bio-based materials have emerged as a viable alternative that can naturally break down and safely decompose in the environment. Despite many studies, biopolymers possess limited mechanical and barrier properties, which restricts their potential for use in products. To overcome this limitation, polymer blending can be employed to enhance their final properties and make them more suitable for various applications.

    The objective of this project was to design sustainable food packaging using biopolymers. PHBV, one of the PHA’s bio-based polymers, was blended with other polymers to enhance its properties as a sustainable food packaging material. Through blending, PHAs'physical, chemical, and thermal properties can be enhanced to obtain exceptional films for food packaging purposes.

    Finally, in this work, a bio-based polymer, polyhydroxyalkanoate, was used to producea biodegradable packaging system for potential food packaging applications. The effect of the physical modification of PHBV on mechanical and barrier properties was studied by blending it with biodegradable polymers such as PLA and PBAT. Thermal properties were analyzed using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and FourierIItransform infrared spectroscopy (FTIR) while the mechanical properties were evaluated by tensile test. Barrier properties were characterized using water vapor transmission rate (WVTR).

    The mechanical performance of PHBV 50%: PBAT 50% blend has been significantly improved, leading to better tensile properties. The high crystallinity of the PHBV 50%: PBAT 50% blend than other blends have been found to enhance the barrier properties of the polymer film, according to DSC analysis. FTIR investigations have suggested no difference in absorption peaks between the blends and the neat material. Furthermore, WVTR investigations have shown that PHBV50%: PBAT50% exhibits excellent barrier properties against water vapor, making it a highly promising material.

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  • 2.
    Asadollahzadeh, Mohammadtaghi
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Mahboubi, Amir
    University of Borås, Faculty of Textiles, Engineering and Business.
    Taherzadeh, Mohammad J
    University of Borås, Faculty of Textiles, Engineering and Business.
    Åkesson, Dan
    University of Borås, Faculty of Textiles, Engineering and Business.
    Lennartsson, Patrik R.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Application of Fungal Biomass for the Development of New Polylactic Acid-Based Biocomposites2022In: Polymers, E-ISSN 2073-4360, Vol. 14, no 9Article in journal (Refereed)
    Abstract [en]

    Fungal biomass (FB), a by-product of the fermentation processes produced in large volumes, is a promising biomaterial that can be incorporated into poly(lactic acid) (PLA) to develop enhanced biocomposites that fully comply with the biobased circular economy concept. The PLA/FB composites, with the addition of triethyl citrate (TEC) as a biobased plasticizer, were fabricated by a microcompounder at 150 °C followed by injection molding. The effects of FB (10 and 20 wt %) and TEC (5, 10, and 15 wt %) contents on the mechanical, thermal and surface properties of the biocomposites were analyzed by several techniques. The PLA/FB/TEC composites showed a rough surface in their fracture section. A progressive decrease in tensile strength and Young’s modulus was observed with increasing FB and TEC, while elongation at break and impact strength started to increase. The neat PLA and biocomposite containing 10% FB and 15% TEC exhibited the lowest (3.84%) and highest (224%) elongation at break, respectively. For all blends containing FB, the glass transition, crystallization and melting temperatures were shifted toward lower values compared to the neat PLA. The incorporation of FB to PLA thus offers the possibility to overcome one of the main drawbacks of PLA, which is brittleness.

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  • 3.
    Bahrami, Bahador
    et al.
    Department of Chemical Engineering, Isfahan University of Technology, Isfahan, 84156-83111 Iran.
    Behzad, Tayebeh
    Department of Chemical Engineering, Isfahan University of Technology, Isfahan, 84156-83111 Iran.
    Salehinik, Fatemeh
    Department of Chemical Engineering, Isfahan University of Technology, Isfahan, 84156-83111 Iran.
    Zamani, Akram
    University of Borås, Faculty of Textiles, Engineering and Business.
    Heidarian, Pejman
    School of Engineering, Deakin University, Geelong, VIC, 3216 Australia.
    Incorporation of Extracted Mucor indicus Fungus Chitin Nanofibers into Starch Biopolymer: Morphological, Physical, and Mechanical Evaluation2021In: Starch, ISSN 0038-9056, Vol. 73, no 7-8, article id 2000218Article in journal (Refereed)
    Abstract [en]

    Bio-nanocomposites based on starch are reinforced by different percentages of chitin nanofibers (ChNFs) and compatibilized by glycerol. Nanofibers are extracted from Mucor indicus fungus through different chemo-mechanical pretreatments. The mechnical, chemo-physical, and morphological properties of the nanocomposite starch films were evaluated and compared with the unfilled thermoplastic starch (TPS) film. Based on the obtained results, Young's modulus of the film at 5 wt.% ChNFs indicated 239% enhancement compared to the TPS film due to the existence of good interactions between starch and ChNFs. Moreover, the ultimate strength of the reinforced film at 5 wt.% ChNFs and the unreinforced counterpart are found to be 5.5 and 1.74 MPa, indicating 216% improvement; however, the elongation at break of the films decreases from 59.3% to 19.3% by adding 5 wt.% ChNFs. In addition, the moisture absorption of the film decreases after the incorporation of ChNFs. Based on the morphological study, ChNFs increase the roughness of the starch matrix with a homogenous morphology revealing the good dispersion of nanofibers in the TPS film. Finally, the nanocomposite film with 5 wt.% ChNFs show the best properties to employ for bio-film applications.

  • 4.
    Bakare, Fatimat O.
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Ramamoorthy, Sunil Kumar
    University of Borås, Faculty of Textiles, Engineering and Business.
    Åkesson, Dan
    University of Borås, Faculty of Textiles, Engineering and Business.
    Skrifvars, Mikael
    University of Borås, Faculty of Textiles, Engineering and Business.
    Thermomechanical properties of bio-based composites made from a lactic acid thermoset resin and flax and flax/basalt fibre reinforcements2016In: Composites. Part A, Applied science and manufacturing, ISSN 1359-835X, E-ISSN 1878-5840, Vol. 83, p. 176-184Article in journal (Refereed)
    Abstract [en]

    Low viscosity thermoset bio-based resin was synthesised from lactic acid, allyl alcohol and pentaerythritol. The resin was impregnated into cellulosic fibre reinforcement from flax and basalt and then compression moulded at elevated temperature to produce thermoset composites. The mechanical properties of composites were characterised by flexural, tensile and Charpy impact testing whereas the thermal properties were analysed by dynamic mechanical thermal analysis (DMTA) and thermogravimetric analysis (TGA). The results showed a decrease in mechanical properties with increase in fibre load after 40 wt.% for the neat flax composite due to insufficient fibre wetting and an increase in mechanical properties with increase fibre load up to 60 wt.% for the flax/basalt composite. The results of the ageing test showed that the mechanical properties of the composites deteriorate with ageing; however, the flax/basalt composite had better mechanical properties after ageing than the flax composite before ageing.

  • 5. Blomberg, Pontus
    Syntetiskt pärlemor: Producerat via in situ-kristallisation2023Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This thesis describes a sequence of experiments which have been performed with the intention to produce synthetic nacre. Synthetic nacre is a biomimetic material based on nacre, a material which can be found in mollusc shells. Nacre is a nanocomposite which has improved mechanical properties compared to the principal component aragonite (95% wt%). The improved properties of nacre are derived from the polymeric components in the composite which allows from redistribution of forces under load. Carbonates sequester CO2 in the geological CO2-cycle. If precursor are sourced correctly, the CaCO3 in synthetic nacre can temporarily sequester CO2.

    Crystals with the intended pseudohexagonal morphology have been synthesised. However, subsequent quantitative analysis could not support these findings in a follow-up experiment. This discrepancy might have been caused by differences in the method. Moist nanopaper was found to be mineralisable while maintaining a layered structure.

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  • 6.
    Duzyer Gebizli, Sebnem
    et al.
    Department of Textile Engineering, Faculty of Engineering, Bursa Uludag University, Bursa, Turkey.
    Guclu, Nihal
    Department of Polymer Materials, Graduate School of Natural and Applied Sciences, Bursa Uludag University, Bursa, Turkey.
    Tiritoglu, Mehmet
    Department of Textile Engineering, Faculty of Engineering, Bursa Uludag University, Bursa, Turkey.
    Tezel, Serkan
    Department of Textile Engineering, Faculty of Engineering, Bursa Uludag University, Bursa, Turkey.
    Orhan, Mehmet
    University of Borås, Faculty of Textiles, Engineering and Business.
    Reversible Thermochromic Polycaprolactone Nanofibers for Repetitive Usage2023In: Fibers And Polymers, ISSN 1229-9197, E-ISSN 1875-0052, Vol. 24, no 10, p. 3393-3403Article in journal (Refereed)
    Abstract [en]

    Color change technology offers unique and challenging opportunities. Thermo-responsive color-changing nanofibers with reversibility have great potential as thermal sensors due to their increased sensitivity and fast response. Herein, polycaprolactone (PCL) nanofibers were produced by adding a leuco-based thermochromic dye with various concentrations (1%, 3%, and 5% wt corresponding to PCL1, PCL3, and PCL5, respectively). The color-changing properties with repetitive heating and cooling were studied, and the effect of dye concentration on the nanofiber properties was determined. The surface properties, dye presence, thermal and mechanical properties were analyzed by SEM–EDS, FTIR, DSC, and tensile tests. Finally, the color change properties were monitored by 1000 heating and cooling cycles between 20 and 40 °C. Thermochromic PCL nanofibers were successfully produced by electrospinning. However, some agglomerates were observed on the nanofibers with increasing dye concentration in SEM images. It was seen that the optimum dye concentration was 3% in terms of the electrospinnability. For PCL5, both presence of carbon, oxygen, nitrogen, and fluorine in EDS spectra, the shifted peaks at 2917 and 2849 cm−1, and the new peaks at 1558, 1517, 1330, 1274, 1213 and 883 cm−1 in FTIR spectra confirmed that dye had been successfully incorporated into the PCL structure. The dye addition caused a decrease in the crystallization degrees, which resulted in lower mechanical properties. PCL5 had the lowest modulus. Color measurements showed that 1% of dyes concentration was not sufficient for the thermochromic property, and the color change was still visually detectable for PCL3 and PCL5 even after 1000 heating and cooling cycles. Color change activation temperature (TA) was confirmed between 30 and 32 °C, and the stability of color change was confirmed for 1000 heating and cooling cycles. After 1000 heating and cooling cycles, the color change was still detectable for PCL3 and PCL5. Consequently, this study showed that reversible thermochromic PCL nanofibers could be promising materials for future sensor applications.

  • 7. Fatarella, Enrico
    et al.
    Corsi, Leopoldo
    Nesti, Solitario
    Mylläri, Ville
    Järvelä, Pentti
    Skrifvars, Mikael
    University of Borås, Faculty of Textiles, Engineering and Business.
    Syrjala, Seppo
    Polymeric composition comprising functionalized PEEK2014Patent (Other (popular science, discussion, etc.))
    Abstract [en]

    The present invention relates to a polymeric composition comprising functionalized polyetheretherketone (PEEK) of formula (II), in admixture with a co-polymer having a melting point lower than the melting point of the non-functionalized PEEK of formula (I). The invention further relates to the use of said composition for the preparation of fibers having antibacterial, decontaminant and self-cleaning properties, useful, for example, for making sanitary garments, such as sanitary coats and masks and for making, for example, filters for ventilation systems and filters for kitchen hoods.

  • 8.
    Fatarella, Enrico
    et al.
    Next Technology Tecnotessile Società Nazionale di Ricerca s.r.l.
    Mylläri, Ville
    Tampere University of Technology.
    Ruzzante, Marco
    Next Technology Tecnotessile Società Nazionale di Ricerca s.r.l.
    Pogni, Rebecca
    Department of Biotechnology, Chemistry and Pharmacy, University of Siena.
    Baratto, Maria
    Department of Biotechnology, Chemistry and Pharmacy, University of Siena.
    Skrifvars, Mikael
    University of Borås, Faculty of Textiles, Engineering and Business.
    Syrjälä, Seppo
    Tampere University of Technology.
    Järvelä, Pentti
    Tampere University of Technology.
    Sulfonated polyetheretherketone/polypropylene polymer blends for the production of photoactive materials2015In: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, Vol. 132, no 8Article in journal (Refereed)
  • 9.
    Fazelinejad, Samaneh
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Åkesson, Dan
    University of Borås, Faculty of Textiles, Engineering and Business.
    Skrifvars, Mikael
    University of Borås, Faculty of Textiles, Engineering and Business.
    Repeated mechanical recycling of polylactic acid filled with chalk2017In: Progress in Rubber, Plastics and Recycling Technology, ISSN 0266-7320, E-ISSN 1478-2413, p. 1-16Article in journal (Refereed)
    Abstract [en]

    Polylactic acid (PLA) was compounded with 30 wt% chalk and 5 wt% of a biobased plasticiser on a twin screw extruder. Mechanical recycling of the obtained compound was studied by multiple extrusions up to six cycles. The degradation was monitored by mechanical and thermal tests. Tensile and flexural tests did not reveal any major degradation after six cycles of processing. Characterising the material with differential scanning calorimetry (DSC) did not detect any significant change of the thermal properties. The material was also characterised by FTIR and, again, no significant change was detected. The material was finally characterised by melt flow index and by proton nuclear magnetic resonance (1H-NMR). Both tests revealed that some degradation had occurred. The 1H-NMR clearly showed that the chain length had been reduced. Also, the MFI test showed that degradation had occurred. However, the study reveals that PLA filled with chalk can be recycled by repeated extrusion for up to 6 cycles, without severe degradation. This should be of relevance when considering the end-of-life treatment of polymer products made from PLA.

  • 10.
    Fulmali, Abhinav Omprakash
    et al.
    FRP Composites Laboratory, Metallurgical and Materials Engineering Department National Institute of Technology Rourkela India.
    Kumar Ramamoorthy, Sunil
    University of Borås, Faculty of Textiles, Engineering and Business.
    Prusty, Rajesh Kumar
    FRP Composites Laboratory, Metallurgical and Materials Engineering Department National Institute of Technology Rourkela India;Center for Nanomaterials National Institute of Technology Rourkela India.
    Water diffusion kinetics study at different hydrothermal bath temperatures and subsequent durability studies of CNT embedded fibrous polymeric composites: Roles of CNT content, functionalization and in‐situ testing temperature2023In: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, Vol. 140, no 11Article in journal (Refereed)
    Abstract [en]

    Although structural polymers like epoxy are extensively used in marine applications over metallic structures, environmental water tends to ingress into this polymer which may affect its long-term durability. The extent of degradation caused by the absorbed water on polymeric composite's mechanical properties depends on the water diffusion mechanism, environmental temperature and subsequent reversible and irreversible chemical restructuring of the polymer. In this study, hydrothermal conditioning behavior of glass fiber reinforced epoxy (GE) composites with varying (0.1, 0.3, and 0.5) wt.% of pristine and functionalized carbon nanotubes (CNTs and FCNTs) was studied at 15°C (Low-Temperature Hydrothermal Conditioning (LTHC)) and 50°C (Elevated-Temperature Hydrothermal Conditioning (ETHC)) water baths. The changes in chemical bonding characteristics and glass transition temperature of GE composite due to above mentioned factors have been studied by Fourier transformed infrared spectroscopy and differential scanning calorimetry. The gravimetric analysis was employed to monitor the water uptake kinetics of the composites and flexural strength of conditioned composites after 50 days of conditioning and saturation was study to understand the effect of water sorption. Experimental results revealed that, FCNTs greatly hinders the water absorption through the interfaces at LTHC, as the equilibrium water content of 0.1FCNT-GE composite was ~9.5% and ~3.0% and Diffusion coefficient was ~60.0% and ~15.5% lower than the GE and 0.1CNT-GE composites, respectively at LTHC. At LTHC, the water saturated 0.1FCNT-GE composites exhibited superior flexural strength than GE and 0.1CNT-GE composites. At ETHC, generation of hygroscopic stresses and unfavorable stresses at the weak CNT/polymer interface adversely affected the 0.1CNT-GE composites water resistance compared to 0.1FCNT-GE composites with stronger FCNT/polymer interface. The extent of recovery in the flexural strength was evaluated by complete desorption of water-saturated specimens. Finally, a fractography study was conducted to understand the variation in the well-being of the glass fiber/polymer and nanotube/polymer interface due to mentioned varying factors.

  • 11.
    Gaurangkumar Mistry, Snehaben
    University of Borås, Faculty of Textiles, Engineering and Business.
    Development Of Bio-Based Thermosetting Resins2021Independent thesis Advanced level (degree of Master (Two Years)), 80 credits / 120 HE creditsStudent thesis
    Abstract [en]

    Thermoset polymers are widely used polymers in the world, but Increase in global plastic pollution and lack of fossil fuel stimulates intense research towards environmentally sustainable materials. Bio-based unsaturated polyesters (UPs) would be an excellent solution to replace oil-based synthetic polyesters. Most of the unsaturated polyesters have been synthesised by ring opening polymerisation (ROP) of cyclic esters or lactides. 

    In this study, different resins were developed using different initiators such as isosorbide (IS),1,4 butanediol (BD), and cis-2 butene 1,4 diol (C2BD) with monomers like lactide (L) and alpha angelica lactone (AAL) through the ring opening polymerisation process. The produced resins were further characterised by using Fourier Transform Infrared Spectroscopy (FTIR),Nuclear Magnetic Resonance (NMR), Thermogravimetric Analysis (TGA), Differential Scanning Calorimeter (DSC), and Dynamic Mechanical Analysis (DMA). 

    Synthesis of resin with lactone monomer was not successful while with lactide monomer it was successful. IS-based resin showed better thermal properties compared to other obtained resins. Tg value of IS containing resin was 63°C, thermal stability up to 235°C and Storage modulus about 3841 MPa. These values are comparable with other bio-based resins produced using the same monomer. 

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    DEVELOPMENT OF BIO-BASED THERMOSETTING RESINS
  • 12.
    Gomes Hastenreiter, Lara Lopes
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Kumar Ramamoorthy, Sunil
    University of Borås, Faculty of Textiles, Engineering and Business.
    Srivastava, Rajiv
    Department of Textile Technology, Indian Institute of Technology Delhi, New Delhi 110 016, India.
    Yadav, Anilkumar
    Department of Textile Technology, Indian Institute of Technology Delhi, New Delhi 110 016, India.
    Zamani, Akram
    University of Borås, Faculty of Textiles, Engineering and Business.
    Åkesson, Dan
    University of Borås, Faculty of Textiles, Engineering and Business.
    Synthesis of Lactic Acid-Based Thermosetting Resins and Their Ageing and Biodegradability2020In: Polymers, E-ISSN 2073-4360, no 12, p. 1-17Article in journal (Refereed)
    Abstract [en]

    The present work is focused on the synthesis of bio-based thermoset polymers and their thermo–oxidative ageing and biodegradability. Toward this aim, bio-based thermoset resins with different chemical architectures were synthesized from lactic acid by direct condensation with ethylene glycol, glycerol and pentaerythritol. The resulting branched molecules with chain lengths (n) of three were then end-functionalized with methacrylic anhydride. The chemical structures of the synthesized lactic acid derivatives were confirmed by proton nuclear magnetic resonance spectroscopy (1H-NMR) and Fourier transform infrared spectroscopy (FT–IR) before curing. To evaluate the effects of structure on their properties, the samples were investigated by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and the tensile testing. The samples went through thermo-oxidative ageing and biodegradation; and their effects were investigated. FT-IR and 1H-NMR results showed that three different bio-based resins were synthesized using polycondensation and end-functionalization. Lactic acid derivatives showed great potential to be used as matrixes in polymer composites. The glass transition temperature of the cured resins ranged between 44 and 52 °C. Pentaerythritol/lactic acid cured resin had the highest tensile modulus and it was the most thermally stable among all three resins. Degradative processes during ageing of the samples lead to the changes in chemical structures and the variations in Young’s modulus. Microscopic images showed the macro-scale surface degradation on a soil burial test.

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  • 13.
    Gtadesse, Melkie
    et al.
    Bahir Dar University, Ethiopian Institutes of Textile and Fashion Technology, 608 Bahir Dar, Ethiopia.
    Loghin, Emil-Constantin
    Bahir Dar University, Ethiopian Institutes of Textile and Fashion Technology, 608 Bahir Dar, Ethiopia.
    Nierstrasz, Vincent
    University of Borås, Faculty of Textiles, Engineering and Business.
    Loghin, Maria-Carmen
    Bahir Dar University, Ethiopian Institutes of Textile and Fashion Technology, 608 Bahir Dar, Ethiopia.
    Quality inspection and prediction of the comfort of fabrics finished with functional polymers2020In: INDUSTRIA TEXTILA, ISSN 1222-5347, Vol. 71, no 4, p. 340-349Article in journal (Refereed)
    Abstract [en]

    Textile’s primary hand (HV) and total hand values (THV) are very important parameters and are used to identify the quality of clothing comfort. This paper aims to predict the HV and THV of the fabrics finished with functional polymers by applying Kawabata’s translation equations. The mechanical properties were achieved using Kawabata’s fabric evaluation system (KES-F) and the inference/interpretation was drawn. Then, HV and THV predictions were performed by applying Kawabata’s translation equations of the KN-101 and KN-301 series. The KES-F result confirmed that it is possible to observe the operative finishing effect on the mechanical properties of fabrics. The prediction results show that the total quality comfort of the functional fabrics could able be estimated by the equation developed by Kawabata; the calculated errors (similar to 0.66) were within the range of the standard deviations (similar to 0.78) of the samples between the predicted and ranked THV. The experimental and the calculated primary hand values showed strong correlation coefficients up to similar to 0.98 which is significant at 0.001 confidence levels. As actual functional fabrics with various surface properties were provided to estimate their tactile comfort via the equations, the result verified that the equation is reliable for the tactile comfort evaluation and grading.

  • 14.
    Hashemi Sanatgar, Razieh
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business. NSAIT, ULR 2461-GEMTEX-Génie et Matériaux Textiles, Université de Lille, F-59000 Lille, France; .College of Textile and Clothing Engineering, Soochow University, Suzhou 215006, China..
    Cayla, Aurélie
    ENSAIT, ULR 2461—GEMTEX—Génie et Matériaux Textiles, Université de Lille, F-59000 Lille, France.
    Guan, Jinping
    College of Textile and Clothing Engineering, Soochow University, Suzhou 215006, China.
    Chen, Guoqiang
    College of Textile and Clothing Engineering, Soochow University, Suzhou 215006, China.
    Nierstrasz, Vincent
    University of Borås, Faculty of Textiles, Engineering and Business.
    Campagne, Christine
    ENSAIT, ULR 2461—GEMTEX—Génie et Matériaux Textiles, Université de Lille, F-59000 Lille, France.
    Piezoresistive Properties of 3D-Printed Polylactic Acid (PLA) Nanocomposites2022In: Polymers, E-ISSN 2073-4360, Vol. 14, no 15, article id 2981Article in journal (Refereed)
    Abstract [en]

    An increasing interest is focused on the application of 3D printing for sensor manufacturing. Using 3D printing technology offers a new approach to the fabrication of sensors that are both geometrically and functionally complex. This work presents the analysis of the 3D-printed thermoplastic nanocomposites compress under the applied force. The response for the corresponding resistance changes versus applied load is obtained to evaluate the effectiveness of the printed layer as a pressure/force sensor. Multi-walled carbon nanotubes (MWNT) and high-structured carbon black (Ketjenblack) (KB) in the polylactic acid (PLA) matrix were extruded to develop 3D-printable filaments. The electrical and piezoresistive behaviors of the created 3D-printed layers were investigated. The percolation threshold of MWNT and KB 3D-printed layers are 1 wt.% and 4 wt.%, respectively. The PLA/1 wt.% MWNT 3D-printed layers with 1 mm thickness exhibit a negative pressure coefficient (NPC) characterized by a decrease of about one decade in resistance with increasing compressive loadings up to 18 N with a maximum strain up to about 16%. In the cyclic mode with a 1 N/min force rate, the PLA/1 wt.% MWNT 3D-printed layers showed good performance with the piezoresistive coefficient or gauge factor (G) of 7.6 obtained with the amplitude of the piezoresistive response (Ar) of about -0.8. KB composites could not show stable piezoresistive responses in a cyclic mode. However, under high force rate compression, the PLA/4 wt.% KB 3D-printed layers led to responses of large sensitivity (Ar = −0.90) and were exempt from noise with a high value of G = 47.6 in the first cycle, which is a highly efficient piezoresistive behavior.

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  • 15. Kalantar Mehrjerdi, Adib
    et al.
    Skrifvars, Mikael
    University of Borås, Faculty of Textiles, Engineering and Business.
    Geothermal pipe collector2014Patent (Other (popular science, discussion, etc.))
    Abstract [en]

    A geothermal pipe collector is provided. The geothermal pipe collector is made from a polymer composition comprising: more than 50wt% polyethylene, 0.1wt% -35wt% talc and 0.5wt% -10wt% carbon black.

  • 16.
    Khalili, Pooria
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business. Swedish Centre for Resource Recovery, Faculty of Textiles, Engineering and Business, University of Borås, 510 90 Borås, Sweden.
    Skrifvars, Mikael
    University of Borås, Faculty of Textiles, Engineering and Business. Swedish Centre for Resource Recovery, Faculty of Textiles, Engineering and Business, University of Borås, 510 90 Borås, Sweden.
    Dhakal, Hom Nath
    Advanced Polymers and Composites (APC), School of Mechanical Design and Engineering, University of Portsmouth, Portsmouth PO1 3DJ, UK.
    Dashatan, Saeid Hosseinpour
    Brunel Composite Centre, Brunel University London, London UB8 3PH, UK.
    Danielsson, Mikael
    Albany International AB, 302 41 Halmstad, Sweden.
    Gràcia, Alèxia Feiner
    Department of Textile Technology and Design, Universitat Politècnica de Catalunya-Barcelona Tech—UPC, 08034 Barcelona, Spain.
    Mechanical Properties of Bio-Based Sandwich Composites Containing Recycled Polymer Textiles2023In: Polymers, E-ISSN 2073-4360, Vol. 15, no 18, p. 1-14, article id 3815Article in journal (Refereed)
    Abstract [en]

    In this paper, sandwich composites were produced by compression moulding techniques, and they consisted of regenerated cellulose fabric (rayon) and bio-based polypropylene (PP) to form facings, while virgin and recycled polyamide (PA) textiles were used as core materials. To compare the mechanical performance between sandwich composites and typical composite designs, a control composite was produced to deliver the same weight and fiber mass fraction from rayon and PP. To evaluate the influence of recycled textile on the mechanical properties of the composites, a series of flexural, low velocity impact (LVI) and tensile tests were performed. It was found that the incorporation of thicker PA textile enhanced the bending stiffness by two times and the peak flexural force by 70% as compared to those of control. Substitution of a layer of recycled textile for two layers of rayon provided a good level of impact energy absorption capacity (~28 J) and maximum force (~4893–5229 N). The tensile strength of the four sandwich composites was reported to be in the range of 34.20 MPa and 46.80 MPa. This value was 91.90 for the control composite. The 2D cross-section slices of the composite specimens did not show any evidence of fiber tow debonding, fiber bundle splitting, or delamination.

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  • 17.
    Kopf, Sabrina
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Åkesson, Dan
    University of Borås, Faculty of Textiles, Engineering and Business.
    Hakkarainen, Minna
    School of Engineering Sciences in Chemistry, Biotechnology and Health, Department of Fibre and Polymer Technology, KTH Royal Institute of Technology, Stockholm, Sweden.
    Skrifvars, Mikael
    University of Borås, Faculty of Textiles, Engineering and Business.
    Effect of hydroxyapatite particle morphology on as-spun poly(3-hydroxybutyrate-co-3-hydroxyvalerate)/hydroxyapatite composite fibers2023In: Results in Materials, ISSN 2590-048X, Vol. 20, article id 100465Article in journal (Refereed)
    Abstract [en]

    Hydroxyapatite (HA) has shown very promising results in hard tissue engineering because of its similarity to bone and hence the capability to promote osteogenic differentiation. While the bioactivity of HA is uncontested, there are still uncertainties about the most suitable hydroxyapatite particle shapes and sizes for textile scaffolds. This study investigates the influence of the shape and size of HA particles on as spun fibers of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) and HA, their mechanical and thermal properties as well as their influence on the fiber degradation in simulated blood matrix and their capability to mineralize in simulated body fluid. The key findings were that the different HA particles’ size does not affect the melting temperature and still maintains a thermal stability suitable for fiber production. Tensile testing revealed decreased mechanical properties for PHBV/HA as spun fibers, independently of the particle morphology. However, HA particles with 30 nm in width and 100 nm in length at 1 wt% HA loading achieved the highest tenacity and elongation at break amongst all composite fibers with HA. Besides, the Ca/P ratio of their mineralization in simulated body fluid is the closest to the one of mineralized human bone, indicating the most promising bioactivity results of all HA particles studied.

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  • 18.
    Kopf, Sabrina
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Åkesson, Dan
    University of Borås, Faculty of Textiles, Engineering and Business.
    Skrifvars, Mikael
    University of Borås, Faculty of Textiles, Engineering and Business.
    Textile Fiber Production of Biopolymers - A Review of Spinning Techniques for Polyhydroxyalkanoates in Biomedical Applications2023In: Polymer reviews, ISSN 1558-3724, p. 200-245Article, review/survey (Refereed)
    Abstract [en]

    The superior biocompatibility and biodegradability of polyhydroxyalkanoates (PHAs) compared to man-made biopolymers such as polylactic acid promise huge potential in biomedical applications, especially tissue engineering (TE). Textile fiber-based TE scaffolds offer unique opportunities to imitate the anisotropic, hierarchical, or strain-stiffening properties of native tissues. A combination of PHAs' enhanced biocompatibility and fiber-based TE scaffolds could improve the performance of TE scaffolds. However, the PHAs' complex crystallization behavior and the resulting intricate spinning procedures remain a challenge. This review focuses on discussing the developments in PHA melt and wet spinning, their challenges, process parameters, and fiber characteristics while revealing the lack of an in-depth fiber characterization of wet-spun fibers compared to melt-spun filaments, leading to squandered potential in scaffold development. Additionally, the biomedical application of PHAs other than poly-4-hydroxybutyrate is hampered by a failure of polymer purity to meet the requirements for biomedical applications.

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  • 19.
    Kumar Ramamoorthy, Sunil
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Kuzhanthaivelu, Gauthaman
    Bohlén, Martin
    Research Institutes of Sweden.
    Åkesson, Dan
    University of Borås, Faculty of Textiles, Engineering and Business.
    Waste Management Option for Bioplastics Alongside Conventional Plastics2019In: IRC 2019 International Research Conference Proceedings, 2019Conference paper (Refereed)
    Abstract [en]

    Bioplastics can be defined as polymers derived partly or completely from biomass. Bioplastics can be biodegradable such as polylactic acid (PLA) and polyhydroxyalkonoates (PHA); or non-biodegradable (biobased polyethylene (bio-PE), polypropylene (bio-PP), polyethylene terephthalate (bio-PET)). The usage of such bioplastics is expected to increase in the future due to new found interest in sustainable materials. At the same time, these plastics become a new type of waste in the recycling stream. Most countries do not have separate bioplastics collection for it to be recycled or composted. After a brief introduction of bioplastics such as PLA in UK, these plastics are once again replaced by conventional plastics by many establishments due to lack of commercial composting. Recycling companies fear the contamination of conventional plastic in the recycling stream and they said they would have to invest in expensive new equipment to separate bioplastics and recycle it separately. Bioplastics are seen as a threat to the recycling industry as bioplastics may degrade during the mechanical recycling process and the properties of the recycled plastics are seriously impacted. This project studies what happens when bioplastics contaminate conventional plastics.

    Three commonly used conventional plastics were selected for this study: polyethylene (PE), polypropylene (PP) and polyethylene terephthalate (PET). In order to simulate contamination, two biopolymers, either polyhydroxyalkanoate (PHA) or thermoplastic starch (TPS) were blended with the conventional polymers. The amount of bioplastics in conventional plastics was either 1% or 5%. The blended plastics were processed again to see the effect of degradation. Mechanical, thermal and morphological properties of these plastics were characterized.

     

    The results from contamination showed that the tensile strength and the modulus of PE was almost unaffected whereas the elongation is clearly reduced indicating the increase in brittleness of the plastic. Generally, it can be said that PP is slightly more sensitive to the contamination than PE. This can be explained by the fact that the melting point of PP is higher than for PE and as a consequence, the biopolymer will degrade more quickly. However, the reduction of the tensile properties for PP is relatively modest. It is also important to notice that when plastics are recovered, there will always be a contamination that will reduce the material properties. The reduction of the tensile properties is not necessary larger than if a non-biodegradable polymer would have contaminated PE or PP. The Charpy impact strength is generally a more sensitive test method towards contamination. Again, PE is relatively unaffected by the contamination but for PP there is a relatively large reduction of the impact properties already at 1% contamination.

    PET is polyester and it is by its very nature more sensitive to degradation than PE and PP. PET also have a much higher melting point than PE and PP and as a consequence the biopolymer will quickly degrade at the processing temperature of PET. As for the tensile strength, PET can tolerate 1% contamination without any reduction of the tensile strength. However, when the impact strength is examined, it is clear that already at 1% contamination, there is a strong reduction of the properties. It can also be seen that presence of TPS is more detrimental to PET than PHA is. This can be explained by the fact that TPS contain reactive hydroxyl groups that can react with the ester bond of PET. This will in other words lead to degradation of PET.

    The thermal properties show the change in the crystallinity. As a general conclusion, it can be said that the plastics become less crystalline when contaminated. The blends were also characterized by SEM. Biphasic morphology can be seen as the two polymers are not truly blendable which also contributes to reduced mechanical properties. Recycling of the contaminated polymer shows an increase in crystallinity. This means that when the polymers are processed, polymer degradation occur causing the polymer chains to gradually become shorter which will enhance the crystallization process.

    The study shows that PE is relatively robust againt contamination, while polypropylene (PP) is somewhat more sensitive and polyethylene terephthalate (PET) can be quite sensitive towards contamination.

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  • 20.
    Kumar Ramamoorthy, Sunil
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Skrifvars, Mikael
    University of Borås, Faculty of Textiles, Engineering and Business.
    Rajan, Rathish
    Tampere University of Technology.
    Rainosalo, Egidija
    Centria University of Applied Sciences.
    Thomas, Selvin
    Yanbu Industrial College and Advanced Materials Laboratory.
    Zavasnik, Janez
    Jožef Stefan Institute.
    Vuorinen, Jyrki
    Tampere University of Technology.
    Mechanical, thermal, and burning properties of viscose fabric composites: Influence of epoxy resin modification2018In: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, Vol. 135, no 36Article in journal (Refereed)
    Abstract [en]

    The influence of epoxy resin modification by 3-aminopropyltriethoxysilane (APTES) on various properties of warp knitted viscose fabric is reported in this study. Dynamic mechanical, impact resistance, flexural, thermal properties, and burning behavior of the epoxy/viscose fabric composites are studied with respect to varying content of silane coupling agent. The results obtained forAPTES-modified epoxy resin based composites reinforced with unmodified viscose fabric composites are compared to unmodified epoxy resin based composites reinforced with APTES-modified viscose fabric. The dynamic mechanical behavior of the APTES-modified resin based composites indicates improved interfacial adhesion. The composites prepared from modified epoxy resin exhibited a twofold increase in impact resistance. The improved adhesion between the fiber and modified resin was also visible from the scanning electron microscope analysis of the impact fracture surface. There was less influence of resin modification on the flexural properties of the composites. The 5% APTES modification induced early degradation of composites compared to all other compo-sites. The burning rate of all the composites under study is rated to be satisfactory for use in automotive interior applications.

  • 21.
    Kumar Ramamoorthy, Sunil
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Åkesson, Dan
    University of Borås, Faculty of Textiles, Engineering and Business.
    Skrifvars, Mikael
    University of Borås, Faculty of Textiles, Engineering and Business.
    Rajan, Rathish
    Tampere University.
    Periyasamy, Aravin Prince
    Technical University of Liberec.
    Mechanical performance of biofibers and their corresponding composites2019In: Mechanical and Physical Testing of Biocomposites, Fibre-Reinforced Composites and Hybrid Composites / [ed] Mohammad Jawaid, Mohamed Thariq, Naheed Saba, Woodhead Publishing Limited, 2019Chapter in book (Refereed)
    Abstract [en]

    This chapter focuses on mechanical performance of biofibers such as flax, hemp, and sisal and their effect on mechanical performance when they are reinforced in thermoset and thermoplastic polymers. The aim of this chapter is to present an overview of the mechanical characterization of the biofibers and their corresponding composites. The mechanical characterization includes tensile, flexural, impact, compressive, shear, toughness, hardness, brittleness, ductility, creep, fatigue, and dynamic mechanical analyses. Detailed studies of each test have been widely reported and an overview is important to relate the studies. Studies pertaining to the topics are cited. The most common materials used in biocomposites are biofibers (also called natural fibers) and petroleum-based polymers such polypropylene. The use of renewable materials in biocomposites has increased in the past couple of decades owing to extensive research on cellulosic fibers and biopolymers based on starch or vegetable oil. Today, research is focused on reinforcing natural fibers in petroleum-based polymers. However, the emphasis is shifting toward the amount of renewable materials in biocomposites, which has led to the use of biopolymers instead of petroleum-based polymers in composites. The mechanical properties of some renewable resource-based composites are comparable to commercially available nonrenewable composites.

    Several plant biofibers have been reinforced in thermoplastics or thermosets to manufacture biocomposites because of their specific properties. The Young's modulus of commonly used biofibers such as hemp and flax could be over 50 GPa and therefore they could be good alternatives to glass fibers in several applications. The good mechanical properties of these biofibers influence the composites' mechanical performance when reinforced in polymers. It is important to understand the mechanical performance of these biofibers and biocomposites in a working environment. A detailed discussion about the mechanical performance of commonly used biofibers and composites is provided in this chapter.

  • 22.
    Loubani, Habib
    University of Borås, Faculty of Textiles, Engineering and Business.
    Use of Polyvinyl chloride (PVC) as an aggregate for concrete2023Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This study investigates the use of polyvinyl chloride (PVC) as a partial substitute of natural aggregates in concrete as fine and coarse aggregates. Concrete was prepared by replacing natural aggregates with equal volume of grinded PVC, with volume replacement ratio as 10%, 50% for fine and then 10% and 50% for coarse aggregates. Experiments were performed to investigate the wet density, workability (measured by slump test), compressive strength, elastic modulus, and water absorption of concrete. After checking the particle distribution (sieve analysis), wet density, workability, and compressive strength, since compressive strength of coarse PVC concrete was much less than that of the reference concrete it was decided to continue the investigation using only the fine partial replacements. The results showed that the wet density of concrete gradually decreased with the increase of PVC content, and workability increased with the increase of PVC. Compressive strength decreased by 13 to 20% for fine PVC and 25 to 31% for coarse PVC concrete, as PVC content increased. Also, it was realized that with the increase of PVC content, elastic modulus decreased by 8.7% for 10% fine PVC while 30% for 50% coarse PVC concrete, and water absorption decreased by 27% for 10% fine PVC concrete and 36% for the 50% fine PVC. It is not advisable to replace aggregates with PVC for achieving reference strength of 40 MPa with water to cement ratio. After studying many probabilities of using the PVC aggregates, it was decided to work on the possible maximum and minimum percentages of substitution, where it was chosen to be 10 and 50%.

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  • 23.
    Makhdoumi, Afsaneh
    University of Borås, Faculty of Textiles, Engineering and Business.
    Synthesis and characterization of lactic acid-based elastomers2023Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Synthesized polymer from bio-based and renewable resources reported as an attractive substitution for fossil-fuel based polymers. Therefore, this work has focused on using sustainable material for production of elastomers to reduce the environmental impact of fossil-based elastomers and overcome the shortage of non-renewable fuels.

    In this research (as thesis work) bio-based elastomers (resins synthesized by reacting of lactic acid with 1,4-butanediol in presence of toluene and methanesulfonic acid as solvent and catalyst, respectively. To trace the reaction, the Fourier transform infrared (FT-IR) spectrometer was used for structural characterization of the products. Furthermore, the degree of reaction followed by measuring of the acid value using alkali titration method. To achieve the desirable results, both condensed resins were reacted with caprolactone for ring opening polymerization. The produced resins were finally functionalized using methacrylic anhydride and the structures and thermal properties of the produced resin were characterized using FT-IR, DSC and TGA. In addition, the viscoelastic properties of the resins were investigated using dynamic mechanical analysis (DMA); and elasticity and viscosity of the elastomers measured using tensile testing machine and viscometer, respectively.

    The important result such as viscosity showed the resin with chain length n= 5 had higher viscosity when compared to the resin chain length n=3. This makes the resin (n=5) suitable for applications that need high viscosities. The resin with chain length n=3 had lower viscosity that is suitable for processing at room temperature. Furthermore, the tensile strength results show maximum elongation for resin with chain length n=3 is almost double compared to resin with chain length n=5. The results showed that these bio-based resins are compatible with petrochemical-based resins, due to desirable rubbery properties, melting temperature, also acceptable viscosity, and other good mechanical properties as will be mentioned below.

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  • 24.
    Mujica-Garcia, A
    et al.
    Dipartimento di Ingegneria Civile e Ambientale, Università di Perugia, Italy.
    Hoosmand, Saleh
    Division of Materials Science, Composite Centre Sweden, Luleå University of Technology, Luleå, Sweden .
    Skrifvars, Mikael
    University of Borås, Faculty of Textiles, Engineering and Business.
    Kenny, J M
    Dipartimento di Ingegneria Civile e Ambientale, Università di Perugia, Italy.
    Oksman, Kristiina
    Division of Materials Science, Composite Centre Sweden, Luleå University of Technology, Luleå, Sweden .
    Peponi, L
    Instituto de Ciencia y Tecnología de Polímeros, ICTP-CSIC, Spain.
    Poly(lactic acid) melt-spun fibers reinforced with functionalized cellulose nanocrystals2016In: RSC Advances, E-ISSN 2046-2069, Vol. 6, p. 9221-9231Article in journal (Refereed)
    Abstract [en]

    Poly(lactic acid)-cellulose nanocrystals (PLA/CNC) nanocomposite fibers with 1% weight fraction of nanocrystals were prepared via melt-spinning. In order to improve the compatibility between PLA and the CNC, PLLA chains were grafted onto the CNC surface using a "grafting from" reaction. For comparison, melt-spun PLA fibers and nanocomposites with unmodified CNC were also prepared. The morphology and thermal and mechanical properties of the fibers with different draw ratios were determined. The results of this research show that the surface modification together with drawing resulted in improved fiber properties, which are expected to depend on the alignment of the CNC and PLA molecular chains. The modification is also expected to lead to a flexible interface, which leads to more stretchable fibers. The main conclusion is that PLLA grafting is a very promising approach to improve the dispersion of CNC in PLA, thus creating interfacial adhesion between the phases and making it possible to spin fibers that can be drawn with improved mechanical performance.

  • 25.
    Mylläri, Ville
    et al.
    Tampere University of Technology.
    Fatarella, Enrico
    Next Technology Tecnotessile Società Nazionale di Ricerca s.r.l.
    Ruzzante, Marco
    Next Technology Tecnotessile Società Nazionale di Ricerca s.r.l.
    Pogni, Rebecca
    Department of Biotechnology, Chemistry and Pharmacy, University of Siena.
    Barratto, Maria
    Department of Biotechnology, Chemistry and Pharmacy, University of Siena.
    Skrifvars, Mikael
    University of Borås, Faculty of Textiles, Engineering and Business.
    Syrjälä, Seppo
    Tampere University of Technology.
    Järvelä, Pentti
    Tampere University of Technology.
    Production of sulfonated polyetheretherketone/polypropylene fibers for photoactive textiles2015In: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, Vol. 132, no 39Article in journal (Refereed)
    Abstract [en]

    New photocatalytic fibers made of sulfonated polyetheretherketone (SPEEK)/polypropylene (PP) are melt compounded and melt spun, first on laboratory scale and then on a semi-industrial scale. Fiber spinnability is optimized and the fibers are characterized using mechanical testing, electron paramagnetic resonance (EPR) spectroscopy, and scanning electron microscopy (SEM). According to the results, the fiber spinnability remains at a good level up to 10 wt % SPEEK concentration. Optimal processing temperature is 200°C due to the thermal degradation at higher temperatures. EPR measurements show good and long-lasting photoactivity after the initial irradiation but also decay in the radical intensity during several irradiation cycles. Mechanical tenacity of the SPEEK/PP 5:95 fiber is approximately 20% lower than for otherwise similar PP fiber. The fiber is a potential alternative to compete against TiO2-based products but more research needs to be done to verify the real-life performance.

  • 26.
    Nasr, Shahab
    University of Borås, Faculty of Textiles, Engineering and Business.
    Användning av den vattenbaserade emulsionspolymeren för utveckling avspecifika egenskaper hos tegel och betong: syntes och karakterisering2022Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Improvement properties of building materials are essential. In this dissertation thesis, the main concern had been on synthesizing a new resin to improve the properties of concrete and brick. Solvent-based polymers have been used for many years to improve the quality of building materials. In contrast to solvent-based polymers, water-based emulsion polymers are one of the available solutions that have been used to improve the quality of building materials. Several advantages can be enumerated for water-based emulsion polymers such as lower volatile organic compounds (VOC), easier application, lower carbon dioxide emissions in the production, and fossil resource preservation. Water-based emulsion polymers are synthesized from simple homopolymers to copolymers with various monomers and additives. In this research, the synthesis and characterization of water-based acrylic styrene emulsion copolymer had been the main concern. Acrylic monomers could develop the qualities such as thermoplasticity, water solubility, and a longer lifespan of the polymer, while styrene monomers will impart water resistance and stiffness properties. In this research, the first step had been the synthesis of a water-based emulsion copolymer. Furthermore, considering the importance of biodegradability of the synthesized copolymer, the research followed by the replacement of ingredients such as emulsifiers with higher biodegradability characteristics with eco-friendly by-products, i.e. reducing the microplastic hazards. As a result, the copolymer could be decomposed better, and consequently, problems with the release of microplastics will be reduced. The synthesized water-based acrylic styrene emulsion copolymer was characterized by FTIR, DSC, and TGA. The FTIR results confirmed successful emulsion polymerization of acrylic styrene copolymer. DSC results confirmed the formation of an amorphous thermoplastic type of copolymer with a single glass transition temperature. The TGA result also confirms a single decomposition temperature. The film formation was carried out using a film applicator to evaluate the film formation properties. The substitution of the superseded emulsifiers (both anionic and nonionic) did not alter the characteristics of the synthesized copolymer, while some of the qualities such as water absorbance of the dried copolymer are improved (a water absorption test was carried out). To improve the quality of both synthesized emulsion copolymers (with conventional and superseded emulsifiers), the nanocomposite of the emulsion copolymer was prepared (Cloisite 30B at a concentration of 0.2 to 1 %). The synthesized nanocomposite showed better water resistance in the coating application in contrast with emulsion copolymer.

    The next stage of the research has been concentrated on the application of the synthesized water-based emulsion copolymer to building materials (concrete and brick). The synthesis copolymer has been applied as a coating on the surface of the concrete and bricks. Moreover, the synthesis copolymer was used as one of the ingredients in the mixture of the concrete. The promising results for the coating improved when the synthesis polymer was modified with nanoparticles (Cloisite 30B at a concentration of 1 % weight of the latex). Incorporating the synthesized copolymer in the mixture of concrete caused decreasing in the density of concrete by 4 % ( via air voids formation mechanism). However, water absorption was improved when synthesized copolymer was mixed with the concrete.

    The synthesized copolymer and the nanocomposite is a suitable coating for the concrete and brick. Furthermore, this copolymer is a suitable water-based coating with improved properties in building materials.

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  • 27.
    Ramamoorthy, Sunil Kumar
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Bakare, Fatimat
    University of Borås, Faculty of Textiles, Engineering and Business.
    Herrmann, Rene
    Arcada University of Applied Science.
    Skrifvars, Mikael
    University of Borås, Faculty of Textiles, Engineering and Business.
    Performance of biocomposites from surface modified regenerated cellulose fibers and lactic acid thermoset bioresin2015In: Cellulose, ISSN 0969-0239, E-ISSN 1572-882XArticle in journal (Refereed)
    Abstract [en]

    The effect of surface treatments, silane and alkali, on regenerated cellulose fibers was studied by using the treated fibers as reinforcement in lactic acid thermoset bioresin. The surface treatments were performed to improve the physico–chemical interactions at the fiber–matrix interface. Tensile, flexural and impact tests were used as indicator of the improvement of the interfacial strength. Furthermore, thermal conductivity, viscoelasticity measurements as well as microscopy images were made to characterize the fiber surface treatments and the effect on adhesion to the matrix. The results showed that silane treatment improved the mechanical properties of the composites as the silane molecule acts as link between the cellulose fiber and the resin (the fiber bonds with siloxane bridge while the resin bonds with organofunctional group of the bi-functional silane molecule) which gives molecular continuity in the interphase of the composite. Porosity volume decreased significantly on silane treatment due to improved interface and interlocking between fiber and matrix. Decrease in water absorption and increase in contact angle confirmed the change in the hydrophilicity of the composites. The storage modulus increased when the reinforcements were treated with silane whereas the damping intensity decreased for the same composites indicating a better adhesion between fiber and matrix on silane treatment. Thermogravimetric analysis indicated that the thermal stability of the reinforcement altered after treatments. The resin curing was followed using differential scanning calorimetry and the necessity for post-curing was recommended. Finite element analysis was used to predict the thermal behavior of the composites and a non-destructive resonance analysis was performed to ratify the modulus obtained from tensile testing. The changes were also seen on composites reinforced with alkali treated fiber. Microscopy images confirmed the good adhesion between the silane treated fibers and the resin at the interface.

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  • 28.
    Ramamoorthy, Sunil Kumar
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Bakare, Fatimat Oluwatoyin
    University of Borås, Faculty of Textiles, Engineering and Business.
    Skrifvars, Mikael
    University of Borås, Faculty of Textiles, Engineering and Business.
    Mechanical and thermal properties of the textile bio-composites: measurement and prediction2015In: , 2015Conference paper (Refereed)
  • 29.
    Ramamoorthy, Sunil Kumar
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Åkesson, Dan
    University of Borås, Faculty of Textiles, Engineering and Business.
    Skrifvars, Mikael
    University of Borås, Faculty of Textiles, Engineering and Business.
    Baghaei, Behnaz
    University of Borås, Faculty of Textiles, Engineering and Business.
    Preparation and Characterization of Biobased Thermoset Polymers from Renewable Resources and Their Use in Composites2017In: Handbook of Composites from Renewable Materials, Physico-Chemical and Mechanical Characterization / [ed] Vijay Kumar Thakur, Manju Kumari Thakur, Michael R. Kessler, Hoboken, New Jersey, USA: John Wiley & Sons, 2017, p. 425-457Chapter in book (Refereed)
    Abstract [en]

    This chapter focuses on physicochemical and mechanical characterization of compositesmade from renewable materials. Most common renewable materials used in composites arenatural fibers and polymers based on starch or vegetable oil. The extent of using renewablematerials in biocomposites has increased during the past decade due to extensive research oncellulosic fibers and biobased polymers. Earlier, the research was focused on using the naturalfibers as reinforcement in crude oil-based polymers such as polypropylene. Later, the emphasisshifted to increase the amount of renewable components in the biocomposites which led tothe introductionof biobased resins in the composites. The properties of some biocompositesare today comparable to the properties for commercially available nonrenewable composites.Several plant biofibers have been used as reinforcement in biobased thermoplastics or thermosetsto manufacture biocomposites. Material characterization is important to understand theperformance of these composites under specific environment. Detailed discussion about themechanical and physicochemical characterization is provided in this chapter. Physicochemicalcharacterization includes chemical composition, density, viscosity, molecular weight, meltingtemperature, crystallinity,morphology, wettability, surface tension, water binding capacity,electricalconductivity, flammability, thermal stability, and swelling. Mechanical characterizationincludes tensile, flexural, impact, compressive, shear, toughness, hardness, brittleness, ductility,creep, fatigue, and dynamic mechanical analysis.

  • 30.
    Santamala, Harri
    et al.
    Aalto University, School of Engineering, Department of Applied Mechanics.
    Livingston, R
    Aalto University, School of Engineering, Department of Applied Mechanics.
    Sixta, Herbert
    Aalto University, Aalto University, School of Chemistry, Department of Forest Products Technology.
    Hummel, M
    Aalto University, School of Chemistry, Department of Forest Products Technolog.
    Skrifvars, Mikael
    University of Borås, Faculty of Textiles, Engineering and Business.
    Saarela, Olli
    Aalto University, School of Engineering, Department of Applied Mechanics.
    Advantages of regenerated cellulose fibres as compared to flax fibres in the processability and mechanical performance of thermoset composites2016In: Composites Part A: Applied Science and Manufacturing, ISSN 1359-835X, Vol. 84, p. 377-385Article in journal (Refereed)
    Abstract [en]

    Man-made cellulosic fibres (MMCFs) have attracted widespread interest as the next generation of fibre reinforced composite. However, most studies focused entirely on their performance on single fibre level and little attention has been paid to their behaviour on a larger application scale. In this study, MMCFs were utilized as reinforcement in unidirectionally (UD) manufactured thermoset composites and compared to several commercial UD flax fibre products. Specimens were prepared using a vacuum bag based resin infusion technique and the respective laminates characterized in terms of void fraction and mechanical properties. MMCF laminates had comparable or better mechanical performance when compared to flax fibre laminates. Failure mechanisms of MMCF laminates were noted to differ from those of flax-reinforced laminates. The results demonstrate the potential of MMCFs as a viable alternative to glass fibre for reinforcement on a larger scale of UD laminates. These results were utilized in the Biofore biomaterial demonstration vehicle.

  • 31.
    Seoane Martinez, Fernando
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Lindecrantz, Kaj
    University of Borås, Faculty of Textiles, Engineering and Business.
    Method and apparatus for brain damage detection2011Patent (Other (popular science, discussion, etc.))
    Abstract [en]

    The present invention comprises method and apparatus for detecting injury resulting in pathological processes affecting tissue within a portion of the body in a mammal, particularly a human brain. Said method comprises the steps of applying a first and a second pair of electrodes around the periphery of the portion, generating an alternating current at a known current level and applying said current between the first pair of electrodes, detecting and measuring the alternating voltage developed between the second pair of electrodes, and calculating the impedance of said portion. Further, the alternating current is applied between the first pair of electrodes in a series of increasing frequencies ranging within a known spectrum, and the resistance and the reactance for each frequency are detected and plotted against said frequency. The electrical impedance of said portion is calculated for each frequency and plotted into an impedance plot. Said resistance-reactance-and impedance-plots are finally analyzed, and any notable changes compared to normal spectrum profiles and plots are detected and evaluated.

  • 32.
    Skrifvars, Mikael
    University of Borås, Faculty of Textiles, Engineering and Business.
    Natural fibres for structural composites - concepts and opportunities2015Conference paper (Other academic)
  • 33.
    Skrifvars, Mikael
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Adekunle, Kayode
    Processing of Lyocell fiber mat: An alternative renewable reinforcement in composite manufacturing2015In: Green and Sustainable Chemistry, ISSN 2160-6951, E-ISSN 2160-696X, Vol. 5, no 2, p. 47-54Article in journal (Refereed)
    Abstract [en]

    The carding of the Lyocell cellulose fiber was done with a cylindrical cross lap machine supplied by Cormatex Prato, Italy. Several mats were made by carding and needle punching in order to have a compact and well entangled mat suitable for reinforcement. The speed of the cross lap machine, the frequency of needle punching, the number of times the mat goes through needle punching, the feeding rate of the carded fiber and the depth of needle penetration determined the level of entanglement of the Lyocell fiber which ultimately increased the mechanical properties of the fiber. The good mechanical properties of the carded Lyocell fiber made it a renewable and environmentally friendly alternative as reinforcement in composite manufacturing. Compared with other jute fiber reinforced composites, the mechanical properties of the resulting Lyocell composites were found to be better. Regenerated cellulose fiber (Lyocell) composites were environmentally friendly and the mechanical properties were comparable to those of natural fibers.

  • 34.
    Skrifvars, Mikael
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Ansari, Farhan
    Berglund, Lars
    Nanostructured biocomposites based on unsaturated polyester resin and a cellulose nanofiber network2015In: Composites Science And Technology, ISSN 0266-3538, E-ISSN 1879-1050, Vol. 117, p. 298-306Article in journal (Refereed)
  • 35.
    Skrifvars, Mikael
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Bakare, Fatimat
    University of Borås, Faculty of Textiles, Engineering and Business.
    Åkesson, Dan
    University of Borås, Faculty of Textiles, Engineering and Business.
    Bashir, Tariq
    University of Borås, Faculty of Textiles, Engineering and Business.
    Ingman, Petri
    University of Turku.
    Srivastava, Rajiv
    Indian Institute of Technology Delhi.
    Synthesis and characterisation of unsaturated lactic acid based thermoset bio-resins2015In: European Polymer Journal, ISSN 0014-3057, E-ISSN 1873-1945, Vol. 67, no June 2015, p. 570-582Article in journal (Refereed)
  • 36.
    Skrifvars, Mikael
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Esmaeili, Nima
    Bakare, Fatimat Oluwatoyin
    University of Borås, Faculty of Textiles, Engineering and Business.
    Afshar, Shahrzad
    Åkesson, Dan
    University of Borås, Faculty of Textiles, Engineering and Business.
    Mechanical properties for bio-based thermoset composites made from lactic acid, glycerol and viscose fibers2015In: Cellulose, ISSN 0969-0239, E-ISSN 1572-882X, Vol. 22, no 1, p. 603-613Article in journal (Refereed)
  • 37.
    Skrifvars, Mikael
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Mabille, Colinne
    University of Borås, Faculty of Textiles, Engineering and Business.
    Wojno, Sylvia
    University of Borås, Faculty of Textiles, Engineering and Business.
    Åkesson, Dan
    University of Borås, Faculty of Textiles, Engineering and Business.
    Dhakal, Hom
    University of Portsmouth.
    Zhang, Zhongyi
    University of Portsmouth.
    Resin transfer moulding processing of biocomposites from warp knitted and carded cellulose reinforcements2015Conference paper (Refereed)
  • 38.
    Skrifvars, Mikael
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Pal, Jit
    Department of Textile Technology, Indian Institute of Technology Delhi, New Delhi, India.
    Srivastava, Rajiv K
    Department of Textile Technology, Indian Institute of Technology Delhi, New Delhi, India.
    Nandan, Bhanu
    Department of Textile Technology, Indian Institute of Technology Delhi, New Delhi, India.
    Electrospun composite matrices from tenside-free poly(caprolactone)-grafted acrylic acid/hydroxyapatite oil-in-water emulsions2017In: Journal of Materials Science, ISSN 0022-2461, E-ISSN 1573-4803, Vol. 52, no 4, p. 2254-2262Article in journal (Refereed)
    Abstract [en]

    Composite matrices of poly(ε-caprolactone)-grafted acrylic acid (PCL-g-AA) and hydroxyapatite (HA) were prepared via electrospinning of oil-in-water emulsions. Grafting of varying amounts of AA on PCL was carried out in a twin-screw compounder using benzoyl peroxide as an initiator under inert atmosphere. A solution of PCL-g-AA in toluene, containing HA, comprised the oil phase of the emulsion, while the aqueous phase contained poly(vinyl alcohol) (PVA) as a template polymer. No emulsifier was used in making such emulsions which were found to be stable for more than a month at room temperature. Secondary interactions of AA group of PCL-g-AA with HA and PVA at the oil–water interface provided stability to the emulsion. Uniform composite fibrous matrices were produced from the resultant emulsions under controlled electrospinning conditions. The composite matrices, thus developed using minimal organic solvent, are free from emulsifiers and have high potential to be used in applications including tissue engineering

  • 39.
    Skrifvars, Mikael
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Rajan, Rathish
    Technology Centre Ketek Ltd.
    Rahkonen, Mirva
    Technology Centre Ketek Ltd.
    Rainosalo, Egidija
    Technology Centre Ketek Ltd.
    Modification of epoxy resin and its influence on tensile properties of viscose fabric composite2015In: ICCM20 Programme and book of abstracts, 2015Conference paper (Refereed)
  • 40.
    Skrifvars, Mikael
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Åkesson, Dan
    University of Borås, Faculty of Textiles, Engineering and Business.
    Mabille, Coline
    Wojno, Sylwia
    Zhang, Zhongyi
    University of Portsmouth.
    Dhakal, Hom
    University of Portsmouth.
    Warp knitted and carded regenerated cellulose reinforced biocomposites2015Conference paper (Other academic)
  • 41.
    Soroudi, Azadeh
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Skrifvars, Mikael
    University of Borås, Faculty of Textiles, Engineering and Business.
    Nierstrasz, Vincent
    University of Borås, Faculty of Textiles, Engineering and Business.
    Novel Skin-Electrode Conductive Adhesives to Improve the Quality of Recorded Body Signals in Smart Medical Garments2019In: MDPI Proceedings, ISSN 2504-3900, Vol. 32Article in journal (Refereed)
    Abstract [en]

    A main barrier to widespread use of electrocardiography garments for long term heart monitoring of elderly and patients is a poor skin-electrode signal transfer because of a high contact impedance and sensitivity to movement. This leads to unwanted disturbances and errors in recorded signals when the patient moves or even breathe, affecting the reliability and quality of the signals especially for patients with dry/old skin. In two different projects at the University of Borås, we have developed two novel products to solve the above problem; (1) an ongoing project that has fabricated a reusable and sustainable electro-conductive adhesive applicable between the skin and high-porous textile electrodes, and (2) a patent-pending skin-electrode glue (BioEl Glue®) which is a biocompatible electro-conductive water-soluble glue used between skin and low-porous textile electrodes.

  • 42.
    Syed, Samira
    University of Borås, Faculty of Textiles, Engineering and Business.
    The Development Of Bio-Composite Films From Orange Waste: A Methodological And Evaluation Study Of Material Properties2021Independent thesis Basic level (degree of Bachelor), 180 HE creditsStudent thesis
    Abstract [en]

    Bioplastic research has become more diverse and different types of research on bioplastic production have been conducted from fruits and vegetable waste, for example, orange waste. The wastes that come from oranges contain more than just vitamins, it has soluble sugars, starch, hemicellulose, cellulose, and pectin. The intention of this project was to study the possibility to produce bio-composite films from orange waste, after removing the soluble sugars. It was also to analyze the properties of the material by tensile strength, visual observation, and to find a methodology that suits this study.

    An ultrafine grinder was used to mechanically separate the cellulose fibres, with the intention to compare the fibrillation cycles on the properties of the bio-composite films. A total of 30fibrillation cycle was performed.

    In addition, different film casting strategies were performed and evaluated. The primary plan was to produce a biofilm without the use of chemicals. After the observing the results three new routes for the methodology was developed where the usage of chemicals was be included. The citric acid was used as a solvent for pectin and glycerol was used as a plasticizer. In the first method, different concentration of citric acid and glycerol were added and observed. The combination which gave uniformed films that contained 0.3 g of citric and 0.375 g of glycerol for a 75 ml hydrogel. The second method was to infuse citric acid before grinding the orange waste suspension. Lastly, the third method was to bleach the orange waste before grinding.

    The films that were produced gave interesting results and from the tensile testing implied that an impact was made on the strength by every fibrillation. The amount of glycerol was consistent throughout the project, but by adding different amount of citric acid gave the films differentIIproperties. The same happened when changing the mould of the film. The best values of the films were from the 30th fibrillation, gave the mean value of 31.6 MPa in tensile strength, and had a strain in elongation at 6.1 %. The tensile strength and elongation had increased drastically compared the fifth fibrillation which had 9.8 MPa and 7.6%.

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    THE DEVELOPMENT OF BIO-COMPOSITE FILMS FROM ORANGE WASTE
  • 43.
    Uusi-Tarkka, Eija-Katriina
    et al.
    School of Forest Sciences, Faculty of Science and Forestry, University of Eastern Finland, FI-80101 Joensuu, Finland.
    Levanič, Jaka
    Biotechnical Faculty, Department of Wood Science and Technology, Jamnikarjeva 101, 1000 Ljubljana, Slovenia.
    Heräjärvi, Henrik
    Natural Resources Institute Finland, FI-80130 Joensuu, Finland.
    Kadi, Nawar
    University of Borås, Faculty of Textiles, Engineering and Business.
    Skrifvars, Mikael
    University of Borås, Faculty of Textiles, Engineering and Business.
    Haapala, Antti
    School of Forest Sciences, Faculty of Science and Forestry, University of Eastern Finland, FI-80101 Joensuu, Finland; FSCN Research Centre, Mid Sweden University, SE-85170 Sundsvall, Sweden.
    All-Cellulose Composite Laminates Made from Wood-Based Textiles: Effects of Process Conditions and the Addition of TEMPO-Oxidized Nanocellulose2022In: Polymers, E-ISSN 2073-4360, Vol. 14, no 19, article id 3959Article in journal (Refereed)
    Abstract [en]

    All-cellulose composites (ACCs) are manufactured using only cellulose as a raw material. Biobased materials are more sustainable alternatives to the petroleum-based composites that are used in many technical and life-science applications. In this study, an aquatic NaOH-urea solvent system was used to produce sustainable ACCs from wood-based woven textiles with and without the addition of TEMPO-oxidized nanocellulose (at 1 wt.-%). This study investigated the effects of dissolution time, temperature during hot press, and the addition of TEMPO-oxidized nanocellulose on the mechanical and thermal properties of the composites. The results showed a significant change in the tensile properties of the layered textile composite at dissolution times of 30 s and 1 min, while ACC elongation was the highest after 2 and 5 min. Changes in hot press temperature from 70 °C to 150 °C had a significant effect: with an increase in hot press temperature, the tensile strength increased and the elongation at break decreased. Incorporating TEMPO-oxidized nanocellulose into the interface of textile layers before partial dissolution improved tensile strength and, even more markedly, the elongation at break. According to thermal analyses, textile-based ACCs have a higher storage modulus (0.6 GPa) and thermal stabilization than ACCs with nanocellulose additives. This study highlights the important roles of process conditions and raw material characteristics on the structure and properties of ACCs. 

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    fulltext
  • 44.
    Xu, Yunsheng
    et al.
    Department of Fibre and Polymer Technology, KTH Royal Institute of Technology, Teknikringen 58, 100 44, Stockholm, Sweden.
    Adekunle, Kayode
    Kumar Ramamoorthy, Sunil
    University of Borås, Faculty of Textiles, Engineering and Business.
    Skrifvars, Mikael
    University of Borås, Faculty of Textiles, Engineering and Business.
    Hakkarainen, Minna
    Department of Fibre and Polymer Technology, KTH Royal Institute of Technology, Teknikringen 58, 100 44, Stockholm, Sweden.
    Methacrylated lignosulfonate as compatibilizer for flax fiber reinforced biocomposites with soybean-derived polyester matrix2020In: Composites Communications, ISSN 2452-2139Article in journal (Refereed)
    Abstract [en]

    The poor adhesion between natural fibers and polymer matrix restricts the mechanical performance of natural fiber reinforced composites. Here, lignosulfonate was methacrylated and evaluated as a potential compatibilizer for flax fiber reinforced soybean-derived polyester thermosets. Significant improvement in both tensile and flexural properties of the fiber composites were achieved when the flax fiber mat was treated with methacrylated lignosulfonate solution. In particular, the flexural modulus and flexural strength more than doubled from 2.6 to 6.7 GPa and from 36 MPa to 76.8 MPa, respectively when the fibers were soaked in 5 wt % MLS solution. The SEM analysis revealed improved fiber-matrix interface and lower extent of fiber pull-out in the methacrylated lignosulfonate treated fiber composites, which correlates with the improved mechanical properties.

  • 45.
    Yandrapu, Sagar
    et al.
    National Institute of Technology, India.
    Gangineni, Pavan
    National Institute of Technology, India.
    Kumar Ramamoorthy, Sunil
    University of Borås, Faculty of Textiles, Engineering and Business.
    Ray, Bankim
    National Institute of Technology, India.
    Prusty, Rajesh
    National Institute of Technology, India.
    Effects of electrophoretic deposition process parameters on the mechanical properties of graphene carboxyl-grafted carbon fiber reinforced polymer composite2020In: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628Article in journal (Refereed)
    Abstract [en]

    Carbon fiber (CF) modification by grafting of various graphene-based nanofillers (GBN) by electrophoretic deposition (EPD) technique was proven to be a successful technique to enhance the out-of-plane performance of carbon fiber reinforced polymer (CFRP) composites. Graphene carboxyl (G-COOH) grafting on carbon fiber by electrophoretic deposition (EPD) is a promising technique to improve the mechanical properties of CFRP composites. To our knowledge, there is a dearth of literature available on the effect of EPD process parameters on the mechanical behavior of modified CFRP composites. The aim of this study is to evaluate the effect of nanofiller concentration in the suspension, applied current, and the time of deposition during EPD on the mechanical behavior of nanophase CFRP composites, thus making it a novel work. With increasing concentration, interlaminar shear strength (ILSS) improved consistently and has shown a maximum enhancement of 24.7% than that of neat CFRP composite at 1.5 g/L nanofiller concentration, whereas flexural strength remained almost unaffected with varying concentration. On the contrary, variation of deposition current has affected the flexural strength but not ILSS. The maximum flexural strength was obtained at a deposition current of 5.0A with an improvement of 16.3% in comparison with neat CFRP samples. However, both flexural strength and ILSS of hybrid CFRP composites have shown improvement with increasing deposition time. At 60 min of deposition, ILSS and flexural strength have shown maximum improvements of 35.0 and 26.6%, respectively, when compared to control specimen. After evaluating the effect of process parameters future scope of the work involves the optimization of parameters for EPD of G-COOH. Fractographic analysis of the fractured samples was performed using scanning electron microscope (SEM) to apprehend prominent failure mechanisms.

  • 46.
    Zanganeh, Farzad
    University of Borås, Faculty of Textiles, Engineering and Business.
    Surface Roughening of PET Meltspun Filament through Minor Phase Removal of Blend2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Superhydrophobic fabrics have gained a huge interest in the industries recently. New legislation pushes the industries to eliminate the use of fluorinated materials in the production of these type of fabrics. Hydrophobic and self-cleaning garments textiles can deliver stable water repellent properties without the need for fluorinated chemicals and reduce the consumption of detergents. New methods that could be implemented in current textile industry processes without major changes in instruments or materials is essential to move this industry to the next level. Filament development with the hydrophobic structure without coating could be strategic on one side and tricky on the other side. It has been proved that a stable hydrophobic self cleaning surface needs a hierarchical micro-nano structure to present sustainable properties. In this thesis, we used common materials in the textile industry for filament production which are polyethylene terephthalate (PET) and high molecular weight polystyrene (PS) and low molecular weight polystyrene (LMPS) to shape the microstructures on the surface of filaments. By adding the common compatibilizer polystyrene-co-maleic anhydride (PSMA) to the blend, PS in the matrix of PET could migrate to the surface. Even 1% wt. of PSMA boosted the migration of PS polymer droplets to the surface. The blend including compatibilizer was compounded, melt-spun into the monofilament, drawn, and annealed for various time durations in the furnace. Next, the filaments were immersed in tetrahydrofuran(THF) to remove the PS component obtaining the rough surface. We investigated the effect of mixture components content and different process parameters such as draw ratio and annealing time on hydrophobicity by the aid of statistical design. Applying the Wilhelmy method for contact angle measurement, we could achieve an advancing contact angle (ACA)of 114º and the average ACA of 96º by making micro-size structure on raw PET with an average ACA of 80º and the intrinsic contact angle of around 70º.

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    fulltext
  • 47.
    Åkesson, Dan
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Bourmaud, Alain
    Beaugrand, Johnny
    Le Duigou, Antoine
    Skrifvars, Mikael
    University of Borås, Faculty of Textiles, Engineering and Business.
    Baley, Christophe
    Recycling of L-Poly-(lactide)-Poly-(butylene-succinate)-flax biocomposite2016In: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321, Vol. 128, p. 77-88Article in journal (Refereed)
    Abstract [en]

    The development of new plant fibre composites is a key point in the development of semi-structural biodegradable or biobased parts, especially for automotive applications. The aim of this original and innovating work is to study, at different scales, the recycling ability of a fully biodegradable L-Poly-(lactide)-Poly-(butylene-succinate)-flax (PLLA-PBS-flax) biocomposite. The biocomposites were manufactured by twin-screw extrusion followed by injection moulding, then the recycling behaviour was studied during successive injection moulding cycles. Firstly, we investigated the length of the flax fibre after compounding and injection, as well as the cell wall stiffness and hardness, by in-situ nanoindentation tests. Secondly, we focused on the effects of recycling on thermal, rheological and tensile properties. We highlighted a severe evolution of the cell wall properties, especially concerning the polysaccharidic matrix after the first thermal cycle, nanoindentation properties remaining quasi-stable after this first drop. Furthermore, the biocomposites did not show any significant evolution of their mechanical performances during cycle three or four of the first injection cycles; after this plateau, the tensile strength and strain as well as impact energy were significantly altered due to the conjugated fibre length decrease and degradation of the PLLA, the latter being emphasized when the flax fibre is embedded. Nevertheless, this fully biodegradable composite exhibits a suitable recycling behaviour for 3 or 4 cycles, which is sufficient for industrial applications.

  • 48.
    Åkesson, Dan
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Fazelinejad, Samaneh
    Skrifvars, Ville-Viktor
    University of Borås, Faculty of Textiles, Engineering and Business.
    Skrifvars, Mikael
    University of Borås, Faculty of Textiles, Engineering and Business.
    Mechanical recycling of polylactic acid composites reinforced with wood fibres by multiple extrusion and hydrothermal ageing2016In: Journal of reinforced plastics and composites (Print), ISSN 0731-6844, E-ISSN 1530-7964, Vol. 35, no 16, p. 1248-1259Article in journal (Refereed)
  • 49.
    Åkesson, Dan
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Fuchs, Torsten
    Stöss, Michael
    Root, Andrew
    MagSol, Helsinki, Finland.
    Stenvall, Erik
    Chalmers tekniska högskola.
    Skrifvars, Mikael
    University of Borås, Faculty of Textiles, Engineering and Business.
    Recycling of wood fiber-reinforced HDPE by multiple reprocessing2016In: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, Vol. 133, no 35Article in journal (Refereed)
    Abstract [en]

    The mechanical recycling of high-density polyethylene (HDPE) reinforced with wood fiber was studied by means of repeated injection moulding. The change in properties during the recycling was monitored by tensile and flexural tests, Charpy impact tests, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), FTIR spectroscopy, and by measuring the fiber lengths. Tests were also done where injection moulding was combined with subsequent accelerated thermo-oxidative ageing and thereafter repeated numerous times. The results showed that the HDPE composites were relatively stable toward both the ageing conditions and the repeated injection moulding. The change of the mechanical properties was mainly observed as an increased elongation at max. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43877. © 2016 Wiley Periodicals, Inc.

  • 50.
    Åkesson, Dan
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Vrignaud, Thomas
    Tissot, Clément
    Skrifvars, Mikael
    University of Borås, Faculty of Textiles, Engineering and Business.
    Mechanical Recycling of PLA Filled with a High Level of Cellulose Fibres2016In: Journal of Polymers and the Environment, ISSN 1566-2543, E-ISSN 1572-8919, Vol. 25, no 3, p. 185-195Article in journal (Refereed)
    Abstract [en]

    Composites consisting of 30 vol% PLA and 70 vol% cellulose fibres were prepared with compression moulding. In the first part of the study, the recyclability of this composite material was investigated by grinding the material and using the recyclate obtained as a filler for PLA. Thus, the recyclate was compounded with PLA in loadings ranging from 20 to 50 wt%. The composites obtained were characterised by tensile tests, Charpy impact tests, DMTA, and SEM. Tests showed that the recyclate had a relatively good reinforcing effect. Stress at break increased from about 50 to 77 MPa and the modulus increased from 3.6 to 8.5 GPa. In the second part of the study, the ability to mechanically recycle the composites obtained was evaluated by repeated processing. Composite with two loadings of the recyclate (20 wt% and 50 %) was injection moulded repeatedly, six times. Tests showed that the composite material with 20 wt% recyclate could withstand six cycles relatively well, while the composite with the higher load degraded much more quickly. For the composites with 50 wt% recyclate, signs of polymer degradation could be seen already after reprocessing the composite once.

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